Re: 2 comments

Greg Burns (gdburns@tbag.osc.edu)
Mon, 24 Jul 95 17:06:51 EDT

>if (myrank == 0)
> MPI_Send(&buff, count, MPI_BYTE, 1, 0, comm);
>else if (myrank == 1)
> MPI_Irecv(&buff, count, MPI_BYTE, 0, 0, comm, &status);
>
>This is a correct (albeit somewhat useless) MPI program: there is no
>requirement to test or wait for each nonblocking call. The MPI standard says
>quite explicitly that the blocking send call must complete, even if the
>receiver never executes a wait or test call.

Where does it say that? In the progress guarantee? As I said earlier,
this is anything but explicit and we interpret it differently. Somewhere else?

The blocking send call could complete when the receiver calls any other
MPI routine.

The only crack I see is whether or not you believe a correct program
must eventually call MPI_Finalize(). If you do not believe so, then
the only danger for the above sender to not complete is for the
the receiver to effectively code while(1); after MPI_Irecv().
This seems like a useless example to force "off-line polling" on
implementations.

--
Greg